Turfgrass Aeration

Over time, many turfgrass soils become compacted, and the thatch layer thickens.  This inhibits efficient water and nutrient use, diminishes root growth, and reduces the overall health of the plants.  The best option for reducing compaction and the thatch layer is core aeration.

ROOT ENVIRONMENT   A strong root system is essential for a green, vigorous lawn.  Healthy roots require sufficient soil pore space for oxygen and water.  Over the years, soils become compacted, and essential pore space is lost due to traffic, settling, gravity, and watering practices. Once soil is compacted, there is insufficient room for oxygen, which drives the metabolic process essential for root growth and water nutrient uptake.  As the roots weaken, the lawn becomes more vulnerable to diseases, insects, weeds and other damage.   COMPACTION   Clay type soils are more vulnerable to compaction, where it occurs more quickly than in sandy or loamy type soils.  However, even coarse or sandy soils can become compacted.  Symptoms indication compaction include: Earthworm castings deposited on top of the soil, making the turf area lumpy and uneven. Lawn must be watered longer because the water does not penetrate well, and tends to runoff quickly. More fertilizer is needed to keep the lawn green. Brown patches occur quickly in the lawn between watering. Lawn looks thinner and shows wear sooner. Weeds become more problematic as the lawn thins and becomes less vigorous. THATCH   Thatch is dead, decomposing roots and stems located on the soil surface.  A thatch layer less than 1/2 inch thick can be beneficial, acting as insulation against solar heating, helping prevent compaction, and conserving moisture.   A heavy thatch layer (more than 1/2 inch thick) can be detrimental, reducing water and nutrient penetration, harbouring insects and diseases, and reducing the overall health and vigor of the the lawn.

COMPACTION AND THATCH CONTROL Aeration Core aeration is the practice of making holes by removing plugs of lawn.  It can be used on all soil types, and is especially beneficial for hard compacted soils.  Some advantages of core aerating include: Deeper water penetration into the soil. Increased oxygen in the root zone. Reduced thatch layer. More efficient use of fertilizer and nutrients. Improved and deeper root growth Reduction of some weeds. Fewer insect and disease problems. Core Aeration is done using a machine that is slightly bigger and heavier than a lawn mower.  Aerating machines pull three to six-inch plugs out of the soil, allowing more air and water space tor the roots.  These soil plugs that are deposited on the grass surface contain microbes which are then available to help decompose the thatch layer. Most cool season grasses can be aerated in the spring, summer, or fall.  The best time, however, is between September and October.  Heavily compacted soil can be aerated both spring and fall, or as often as needed.  Aeration should be done annually on most lawns. When core aerating, be certain the soil is moist, but not wet.  Moist soil allows the aerator to penetrate easier and deeper.  Water the lawn area the day before aerating to allow time to drain most of the excess water before aerating. It is best to leave the plugs on the lawn after aerating.  This allows the microbes from the soil plugs to move down into the thatch layer and break it down.  The lawn can be mowed after aerating, which helps break the plugs up and speed their decomposition. A core aerator can be rented at most rental shops, some nurseries or garden centers, or a professional can be hired to do the work.

CLIPPINGS

OTHER CULTURAL PRACTICES

Contrary to popular belief, leaving clippings on the lawn after mowing does not add to the thatch.  In fact, clippings can actually help reduce the thatch.  In some cases, adding organic matter (clippings) to the top of the thatch provides the microbes with a food source so they can then decompose the thatch.   Another benefit of leaving grass clippings is returning some nitrogen and other nutrients back to the soil.  Test have shown that grass clippings left on the lawn can reduce fertilization costs by as much as 30 percent.

Aerating and leaving the clippings on the lawn are just two practices that can reduce compaction and thick thatch.  Others include: Mow the grass between 2 1/2 and 3 inches high. Water deeply and infrequently to promote deep root growth. Fertilize properly--especially in the fall, to promote healthy root growth Establish permanent paths in well-traveled areas. Keep heavy equipment such as trucks and cars off turfgrass areas. Keep off the turf directly after watering.